A sign warns of petroleum pipelines next to an oil slick along the coast of Refugio State Beach in Goleta, California, United States, May 20, 2015.

California Governor Jerry Brown issued an emergency proclamation on Wednesday for Santa Barbara County where crews are working to clean up the largest oil spill to hit the local coastline in nearly two decades.

"This emergency proclamation cuts red tape and helps the state quickly mobilize all available resources," Brown said in a statement. "We will do everything necessary to protect California's coastline."